Relative folate bioavailability from diets containing human, bovine and goat milk

The present study was designed to determine the relative folate bioavailability from diets containing human, bovine or goat milk and the relative sensitivity of various response criteria used in assessing folate bioavailability. Following a 12-wk depletion period, 16 groups of male rats (n = 5/group) were fed experimental diets with or without 20% milk solids and graded levels of folic acid for 4 wk. Total folates were measured in plasma, erythrocytes, liver and kidney. Bioavailability of dietary folate was determined using slope-ratio statistics. Plasma response was found to be the most sensitive indicator of folate bioavailability based on steepness of slope, goodness of fit (r = 0.96, P 0.01) and linearity of response over the entire range of folate intakes. Kidney folate concentration also showed a significant linear relationship to total folate intake (r